Are you using a XP disk someone made for you?
other then that we need more info about your system & hardware.
Make sure your drives are installed and configured properly. With IDE drives the boot drive should be on the IDE-0 connector and the master drive should be on the end of the cable with the slave in the middle. If you only have 1 drive then check the drives label for how to set it up in single mode (it will still go on the end of the cable)